New components of the hypothalamus which inhibit the release of insulin (insulin release inhibiting factor, IRIF) and stimulate the release of glucagon (glucagon releasing factor GRF) from the endocrine pancreas both in vivo and in vitro, have been detected in extracts of rat tissue. We have provided evidence that these activities are peptides and that IRIF and GRF, as well as being separate entities as judged by their separation by gel-filtration, can each be purified further through three sequential chromatographic manipulations. This proposal describes the continuation of studies on the two peptides leading to isolation of IRIF and GRF using both long established and more recently developed techniques of peptide fractionation from large batches of rat hypothalami to yield homogeneous material for analysis. Application of the purification sequence which we have constructed to large batches of rat hypothalami will yield materal suitable for analysis then sequence determination using highly sensitive automated analytical instrumentations. This information will permit synthesis of the peptides toward proof of their structure and generation of antisera. These are the essential prerequisites to evaluation of the contribution of the two peptides to the complex system whereby mammals use insulin and glucagon to adjust their metabolism in response to fuel intake and expenditure. If the postulated neurohomonal role of these peptides is confirmed it is entirely possible that defects in their production by the hypothalamus may be revealed as contributing to diabetic and obese conditions in the human.